Problem Statement

Given is a sequence of $N$ integers $A_1, \\ldots, A_N$.

Find the (multiplicative) inverse of the sum of the inverses of these numbers, $\\frac{1}{\\frac{1}{A_1} + \\ldots + \\frac{1}{A_N}}$.

Constraints

• $1 \\leq N \\leq 100$
• $1 \\leq A_i \\leq 1000$

Input

Input is given from Standard Input in the following format:

$N$ $A_1$ $A_2$ $\\ldots$ $A_N$

Output

Print a decimal number (or an integer) representing the value of $\\frac{1}{\\frac{1}{A_1} + \\ldots + \\frac{1}{A_N}}$.

Your output will be judged correct when its absolute or relative error from the judge's output is at most $10^{-5}$.

Sample Input 1

2
10 30

Sample Output 1

7.5

$\\frac{1}{\\frac{1}{10} + \\frac{1}{30}} = \\frac{1}{\\frac{4}{30}} = \\frac{30}{4} = 7.5$.

Printing 7.50001, 7.49999, and so on will also be accepted.

Sample Input 2

3
200 200 200

Sample Output 2

66.66666666666667

$\\frac{1}{\\frac{1}{200} + \\frac{1}{200} + \\frac{1}{200}} = \\frac{1}{\\frac{3}{200}} = \\frac{200}{3} = 66.6666...$.

Printing 6.66666e+1 and so on will also be accepted.

Sample Input 3

1
1000

Sample Output 3

1000

$\\frac{1}{\\frac{1}{1000}} = 1000$.

Printing +1000.0 and so on will also be accepted.